Design And Experiment Research Based On Tangential Flow Transverse Axial Flow Corn Threshing System

In the area of maize production in the HuangHuaihai,where two crops are cooked twice a year,the high breakage rate of high moisture content is an important constraint to the development of maize kernel harvest mechanization technology.There are two aspects of the technical approach to solve this problem,one of which is the breeding of early-maturing and rapidly dehydrated varieties suitable for mechanized grain harvesting.Secondly,in the field of corn harvesting machinery,we have researched and developed corn harvest mechanization technology equipment that is suitable for direct grain harvesting in the region.As of 2017,the horizontal axis flow switch wheat harvester in the Huang-Huai-Hai area has more than 97% in total.If the threshing system is based on the structure of the threshing system of the horizontal-axis wheat harvester,the threshing system of the corn grain harvester will be developed and improved.It will bring good economic benefits to the harvesting technology and equipment in the region.This topic starts with the characteristics of corn materials and threshing technology and equipment.It analyzes related research and low damage harvesting technologies at home and abroad.It adopts a combination of theoretical analysis,simulation and experimental verification to conduct experiments on corn biomechanics and tribology characteristics.The analysis,the dynamics of threshing and the kinetics of material separation,established a new type of tangential flow transverse axial flow corn threshing system,through indoor experiments and field experiments to studied the low damage corn grain harvesting,and provided for mechanized low-damage kernel corn harvesting.technical foundation.The main research content of this article is as follows:The corn grain characteristics test was conducted by selecting typical grain yield control varieties,and the change laws and functional equations of water content and grain geometry,volume,grain weight density,and mechanical properties were analyzed.A comprehensive testing device for tribological properties was designed.Through experimental tests,the relationship between moisture content of corn grain,static friction coefficient,rolling friction coefficient,sliding friction coefficient,collision recovery factor and stacking angle of repose was analyzed,and the variation of these characteristic parameters was summarized.The range of parameters of tribological properties under the range of commonly used water content was obtained,providing basic data for numerical simulation of discrete elements.The method of calculating the equivalent pressure of grain is put forward,which provides a standard method for uniform reduction and comparison of the damage of different parts of grain.The paper puts forward the evaluation model and modelling method of corn cultivars for maize grain cultivars,and provides the scientific basis for evaluating the adaptability of different cultivars of cultivars.Combining with the grain compression test test,a maize kernel model was established and finite element software was used to simulate the stress,strain and internal damage of the maize kernel during the extrusion process.In to the domestic and foreign corn harvesting threshing test technology methods,a new type tangential flow transverse axial flow threshing system and test platform for column-tooth-plate-tooth roller mixing are established.Spiral-column-structured flow-cutting drums,grid-type high-strength concave-grained screens,threshing chamber lids with guides and multifunctional adjustable loading devices.The overall structure of the threshing system is designed in a modular way.The key components such as the threshing roller can be replaced and the technical parameters can be adjusted according to the needs,so that a variety of grain threshing experiments can be carried out.In order to verify the rationality and reliability of the mechanical structure design of the test bench,the ADAMS FEM software was used to simulate the dynamic balance of the shear flow and the axial flow rollers,and verified with the dynamic balance test;the ANSYS software was used to simulate The modal analysis,strength check,or fatigue analysis was performed on the dynamic characteristics of the drum shaft and frame,which verified the safety and structural stability of the mechanical design,and provided a reliable test basis for the threshing test.Based on the corn threshing test,the mathematical model of the material threshing separation process in the tangential flow transverse axial flow system was studied,the contact state between the threshing element and the grain,and the critical state of the damage when the grain was subjected to thrashing impact were analyzed;the column teeth and plate were analyzed.The threshing kinetics of the contact between the threshing element and the grain;the discrete element simulation and high-speed photography analysis verify the movement of the material in the threshing separation process,and the derivation of the analytical modelling of the various working conditions of the threshing system and the solution of the relevant resistance coefficients.The fundamental principle of the unsteady operation of the threshing system/the threshing drum is clarified,which provides a technical method for optimizing design of the threshing system and improving the quality of the threshing operation.The threshing test of the tangential flow transverse axial flow system shows that the three-stage structure design of threshing,screening and rejecting can be used to optimize the threshing process of corn and to compensate the threshing of horizontal axial flow models.And short trip problem.The test shows that the proportion of the threshing mass of the tangential flow drum decreases with the increase of the moisture content,the water content is below 28%,and the mass ratio of the threshing material between the tangential flow transverse axial flow threshing screen is almost the same;When the moisture content is higher than 28%,the mass ratio of the threshing material in the tangential flow drum drops significantly.When the corn seed with high moisture content is harvested,the threshing system can fully utilize the threshing system to control threshing and lateral axial flow.ability.In optimizing the structural design of the threshing system for the tangential flow transverse axial flow models,it is necessary to combine shear flow and lateral axial flow in order to effectively reduce the grain broken rate and improve the quality of harvesting operations.The tangential flow transverse axial flow threshing system threshing test of the shuffled drum shows that the drum speed and moisture content are the most critical factors influencing the threshing grain broken rate,followed by the feeding amount and the threshing gap,and the optimal threshing parameter combination obtained by the test is: The axial flow drum peripheral velocity is 5.84~17.28 m/s,the moisture content is 24%~26%,the feed volume is 2.6~3.0 kg/s,and the threshing gap is 34~36 mm.Under the same conditions,the threshing system of the drum-to-plate tooth mixing structure roller is more efficient than the threshing system of the traditional full-column roller structure in the threshing capacity and adaptability of the corn ear with water content above 28%.In terms of satisfying the breakage rate of the kernel specified in the national standard,the column-tooth plate-toothed roller has a wider scope of application of the moisture content and the applicable range of the linear velocity than the conventional full-column roller.For discrete element modeling of corn kernels,an efficient and accurate modeling method based on three-dimensional scanning of corn kernels and shell filling was proposed.Compared with the conventional method of particle coordinate modeling,the computational efficiency was not only greatly improved,but also the experimental error was only 4.45% of the conventional methods provide an efficient and accurate modeling method for discrete element simulation of irregular crop materials.The use of high-speed photography technology to observe the movement process of materials in the threshing room,It has a more intuitionistic understanding of the movement posture,the law of the core and broken core axis,and the process of taking impact and speeding up the separation.The theoretical modeling and analysis of material movement and discrete element simulation of material movement A good demonstration was provided and a technical method was provided for the optimal design of the threshing system.The field grain harvesting test verified the rationality of the broken rate index and the optimal combination result of the horizontal axial flow threshing system of the column-tooth plate tooth mixing roller,and still achieves a maximum of 3.9 under a significant increase in the amount of feed.The grain broken rate and 0.7% impurity rate indicate that the system has a good technical potential.The multi-variety machine harvest test showed that the system has good adaptability to other grain direct harvest varieties.Under the same machine harvest conditions,the average breakage rate and impurity rate of the three varieties tested were reduced by 40.5% compared with traditional threshing systems.33.1% indicates that the lateral axial flow threshing system for designing the column-tooth plate-tooth roller mixing roller has obvious technical advantages over the traditional all-column gear threshing system.